<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>动画体验</title>
    <style>
        @keyframes a_color {
            from {
                color: #333;
            }
            to {
                color: red;
            }
        }
        
        .box {
            animation-name: a_width;
            animation-duration: 8s;
            animation-delay: 3s;
            animation-fill-mode: backwards;
            animation-timing-function: ease-in;
        }
        
        @keyframes a_width {
            25% {
                width: 100%;
                background-color: teal;
                color: red;
                opacity: 0.5;
            }
            75% {
                width: 100px;
                background-color: pink;
            }
        }
    </style>
</head>

<body>
    <div class="box">hello 动画！</div>
</body>

</html>